Uteroferrin (Uf), a progesterone and estrogen regulated uterine secretory glycoprotein is implicated in both fetal development and placental function in the sow. However, its exact roles and mechanism of action in fetal and placental tissues are unknown. This proposal seeks to examine the regulatory mechanisms underlying the temporal and tissue specific expression of Uf as a first step towards the elucidation of its biological significance in development. Towards this end, the regulation of Uf synthesis and secretion will be studied at the level of its gene using current methodologies in gene technology. The complementary DNA (cDNA) for Uf will be isolated from a Lambdagt 11 expression library prepared from porcine uterine endometrial poly (A+) RNA, by screening with sheep polyclonal antibody raised against purified Uf. This clone will be characterized by restriction endonuclease mapping and nucleotide sequence analysis and will be used to evaluate the size and relative abundance of Uf mRNA(s) in uterine endometria of sows during the estrous cycle and pregnancy. These levels of mRNA will then be compared to the Uf protein content in endometrial cells and to the amount of Uf protein secreted by these cells. This will provide information on the temporal regulation of Uf protein and its mRNA during fetal and placental development. The chromosomal gene for Uf will be isolated using cloned cDNA as a probe. Complete elucidation of its nucleotide sequence and genomic organization will allow for comparisons with genes coding for proteins of similar functions and/or regulation and will give insights into the possible mechanism of Uf regulation by sex steroids. Lastly the Uf gene will be expressed in mouse C127 cells or human endometrial cells using bovine papilloma virus as vector in order to delineate the contribution of estrogen and progesterone in the regulation of Uf gene expression and to define the specific genomic regions responsible for this differential regulation. Uteroferrin represents an excellent model system for studying the role of other uterine secretory proteins in fetal and placental development. The proposed work will provide a foundation for further understanding the biological significance of Uf and may clarify the mechanisms underlying maternal-fetal interactions in mammalian systems that are essential for fetal development.